Treatment of nanosized TiO2-containing wastewater by simultaneous electrocoagulation/electrofiltration

In this work, a simultaneous electrocoagulation/electrofiltration (EC/EF) treatment module was employed to treat nanosized TiO2-containing wastewater. Nanosized TiO2-containing wastewater was obtained and treated by a self-designed EC/EF treatment module. To evaluate the performance of this novel treatment module, the effects of electric field strength (EFS), transmembrane pressure (TMP), and crossflow velocity (CV) on permeate qualities were investigated. Permeate qualities of concern included pH, turbidity, conductivity, chemical oxygen demand (COD), and total organic carbon (TOC). A full factorial design of experiments was adopted in this work. First, by keeping TMP and CV constant the effects of EFS on permeate qualities were studied. In this set of testing, it was noticed that an application of electric field greatly increased the filtration rate, which was further influenced by the magnitude of EFS. In all cases, the 14 filtration rate decreased as the treatment time elapsed due mainly to fouling of the membrane. Further tests were conducted to study the effects of TMP on permeate qualities by keeping EFS and CV constant. Finally, the effects of CV on permeate qualities were studied by keeping EFS and TMP constant. It was found that the optimal operating conditions would be electric field strength of 166.7 V/cm, transmembrane pressure of 1 kgf/cm(2), and crossflow velocity of 0.22 cm/s. Under such conditions, permeate would have the following qualities: (1) pH, 6.32; (2) turbidity, 2.41 NTU; (3) conductivity, 15.11 mu S/cm; (4) COD, 100.0 mg/L; and (5) TOC, 512.6 mg/L.